Growth rate of the common bream in lowland European reservoirs with different fish density

The growth rate of bream (Abramis brama) had been estimated in one Czech (l ong-term 15 years study), two English and one Dutch reservoirs. Thermal con ditions of these reservoirs were similar. Natural-banked reservoir (Rimov R eservoir, Czech republic) was characterised by dense fish populations (many hundreds kg/ha), poor presence of larger zooplankton, slow growth rate and relatively small maximum sizes of fish. Bowl type impoundments have low fi sh stocks, large zooplankton and fast fish growth. Despite the fact that br eam is an omnivorous fish, zooplankton seems to be the most preferred food if available. As a key diet component the state of zooplankton can be used for the prediction of the bream growth rate for at least the first four yea rs of life. The only exception from this pattern were the first years after impounding Rimov Reservoir, when the fish were growing fast although the l arge zooplankton was nearly absent due to overgrazing (fish growth was not related to the presence of large zooplankton).